SiYuan before v3.7.4 contains an information disclosure vulnerability in the /api/tag/getTag endpoint that returns tag labels and occurrence counts from password-protected documents to unauthenticated readers. Attackers can enumerate tag vocabulary and internal terminology from password-protected documents by calling the tag endpoint without providing the document's publish password.

Affected: Go: github.com/siyuan-note/siyuan/kernel

**CVE:** This vulnerability corresponds to [CVE-2026-72792](https://nvd.nist.gov/vuln/detail/CVE-2026-72792).

### Summary

`/api/tag/getTag` filters its results for reader roles through `FilterTagsByPublishIgnore`, which checks only the *visible* publish tier. Documents that are published but password-protected pass that check, so a reader who has never entered a document's publish password receives every tag label used inside it, together with occurrence counts.

The project has already treated this exact tier mismatch as a vulnerability on a sibling path: commit `82e9ded42` ("Enforce publish access for graph nodes") moved the graph endpoint off the visible-only filter and onto a password-aware one. `FilterTagsByPublishIgnore` was not upgraded alongside it.

### Details

| Item | Detail | |---|---| | Route | `kernel/api/router.go:194` `POST /api/tag/getTag` → `model.CheckAuth` → `getTag` | | Middleware | `CheckAuth` only: no `CheckReadonly`, no `CheckAdminRole` | | Guard | Present but at the wrong tier: visible-only, no password check | | Exposed | Every tag label (`#label#` text) and its occurrence count inside password-protected but visible documents |

**The tier mismatch.** For reader roles, `getTag` filters via:

```go publishIgnore := GetInvisiblePublishAccess(publishAccess) tags = FilterTagsByPublishIgnore(publishIgnore, tags) ```

`FilterTagsByPublishIgnore` counts a label if `CheckPathAccessableByPublishIgnore(span.Box, span.Path, publishIgnore)` holds, then reads…